Apparatus for the measurement of radiating energy such as exposure meters



, 1939. DEVAUX ET'AL 2,151,901

APPARATUS FOR THE MEASUREMENT OF RADIATING ENERGY SUCH AS EXPOSURE METERS Filed March 13, 1957 2 Sheets-Sheet l 11 2 a /fl l MAW/1mm 27 v 47. I I. x Y 13 I Y INVENTORS lac/4w azwwx 35 REA/E AzP/M/YSEHIGIMIIED March 28,1939. L. DEvAuX Er'A L A FEARA'PUS FOR THE MEASUREMENT OF RADIATING ENERGY SUCH AS EXPOSURE METERS.

' Filed March 13; 1957 2 Sheets-5heet [/f/IIIIIl/IIIIIIII l ATTORNEY directly radiated by a source or reflected by a field Patented Mar. 28, 1939 APPARATUS FOR THE MEASUREMENT OF RADIATING ENERGY SUCH AS EXPOSURE METERS Lucien Devaux and Rene Alphonse Higonnet,

Paris, France, assignors to International Standard Electric Corporation, New York, N. Y.

Application March 13, 1937, Serial No. 130,746 In France March .14, 1936 4 Claims. (01. 88-23) This invention relates-to apparatus used for the measurement of radiating energy, such as exposure meters and namely to various improved arrangements used in said apparatus.

According to certain features of invention, an apparatusci this type comprises two shells fitting in one another and or in which arelocated elements such as: photoelectric cells, optical device, micr'o-ammeter, calculating device.'

According to other features of the invention means are also provided to enable the use of such apparatus for the measurement of energy either of viewof which it is desired to measure the amount. of irradiation.

ing description in relation with the attached drawings in which: 7

Figure 1 isa front view of the inside part of one half shell in which are provided openings allowing to see the indications of the apparatus;

Figure 2 is a sectional longitudinal view of. the complete apparatus with the exception of the calculating device;

Figure 3 is' a transversal sectional view along line AA of apparatus shown on Figures 1 and 2;

,Figure 4 is a half front view of another form of shell used in a modified form of apparatus;

Figure 5 is a sectional longitudinal view of the shell used in such a modification;

Figure 6 is a half sectional'transversal view along line AA of the shell of Figure 5;

Figure 7 shows an improved calculating device which can be usedfor instance with such exposure meters. i

In Figures 1, 2 and 3, which relate to a particular form of exposure meters embodying certain features of theinvention, the same numerals are used for denoting the same elements in the three figures. n

In these figures, I represents a half shell in molded material provided with opening 2 permitting to see the dial 3 of the micro-ammeter and the opening 4 for an adjusting knob (not shown) used to modify the range of sensitivity of the pressed portions I serve to locate one edge of the photoelectric cell 8 and the depressed portion 9, serves to locate the adjusting device of the microammeter; at the bottom of that portion 9 is an opening in permitting the introduction of a pin to control said adjusting device. Holes H are of the. two half shells l and I3, and also a depressed part 14, limited by protruding parts I6 and I1, serves to locate the transparent plate I5.

The half shell I3 is provided with a groove l8 to maintain the other edge of the lens 6 and of a depressed portion I9 to locate the other edge of the photoelectric cell 8. Another depressed portion is used to locate the frame 22 of the movingcoil 23 of the -micro-zau'nmeter, said portion being iurther depressed at 2| to locate the ball bearing 24 of moving coil 23. Thehalf'shell I3 is iurther provided with a hole 25 forethe shaft.

(not shown) of the calculating device such as illustrated in Fig. 7, and is externally'shaped as shownat 26 to allow the fixation ofthe dial oithe calculating device. 1

The assembly of the photoelectric cell andthe micro ammeter is shown in detail on Figures2 and 3, These two elements are supported by a commo'n'frame 21. At one end of saidframe the photoelectric cell 8 is fixed 1 by a bracket '28 integral with a supporting plate 29, said bracket 7 I being. also used to hold on frame 21 the dial 3.0f Q

the micro-ammeter as by screw 30. In frontof [.25 32 of the moving coil 23. The spindle 32 carries dial 3 moves an index 3| carried on {the spindle also on the same side as index 3ljwith respect toa to a bent rod 34 which traverses the bearing35 of spindle 32 and bears against half shell I in front of the elongated opening l'li'in which a small pin can be introduced to control the tension of spring 33. The moving coil 23is surroundedby a cup shaped housing 22 whichis viewed in'a-T form on Figure 3, said housing 22resting on frame 21 and serving to carry by means of bearing 24' v and pivot 36 the spindle 32 of moving coil 23. On that part of spindle 32 is also carried another restoring spring 38. The cup shaped housing 22 is fixed on the frame 21 by screws 39, Fig. 2. The magnet 40 is also supportedby thel'frame 21.

Referring to Figure 3, theadjustin'g device for spindle 32 is clearly shown' 'ahd'comprises a spring blade 4|. fixed to the cup shaped housing 22 by a screw 42 at one end-and at his other end to an adjusting screw 43 which can be screwed in a protruding portion 44 of the housing 22.

The mode of assembly of the two half shells ando'f theelements of the exposure meter is also clearly'visible on said Fig. 3. The half shell I is provided with holes II for molded in elements 45 ;in .which .are screwed the screws l2 which iclanip theirame 21 betweenthe two shells l and used for locating the'two clamping screws I2 'I3 by means of resilient clamping washers 46,

the shells as shown at I m close contact. fjfconstruction a simple mode of a1 5,; different elements is obtained, the gggftnts forming a unitary'block by means n jpammon frame 21, and being not linked ny organ to the two halfshells l and! ,zaking up the housing of the apparatus.

Figures 4, and 6 represent a modified form for the housing an exposure meter making use of certain features of the invention: In these figures, I represents a half shell of molded material provided with an opening 2 for viewing the dial of .7 the micro-ammeter, an opening 53 for the adjusting element'of the calculating device and depressed portions 54 for the bearing rods of the dial and of the moving coil apparatus, 55 and 56 ing the magnet and two blocks 64 integral with micro ammeter. including the magnet. In addiv for the location of the supporting frame of the moving device, 51-for one edge of the photoelectric cell and 58 for the holding of one edge of the toroidal lens 18. on its outer face thehalf shell has in addition a ring shaped depressed portion '59 for the dial'of the calculating device, .A rein-. forcing rib50 is provided as shown. 'I'hetwo half shells are joined by screws the housingsof which are shown at 5]. The half shell 62 is provided on its inner face withfa spacing pieceiilfor supportthe half shell 62 in which are embedded the ends of two screws'55 used to holdthe assembly of a tion depressed portions 66, 61 and groove 68 are provided respectively to locate the bearing of the moving device, the photoelectric cell, and they toroidal lens l8. Figure 6 shows the manner of holding thephotoelectric cell which bears upon the bottom of depression 61 on an embossed part provided with a groove 69 in which a blocking rod not shown can be forced. The other end of cell is held in a similar manner but the groove for the blocking rod is provided on the other face of the housing with respect to that shown on the figure. An improved type of calculating device whic can be used namely but not exclusively with these two forms of exposure meter is provided to give useful indications fortwo diiferent types of measurements for determining time of exposure. This device which is shown on Figure 7 is represented in the form of a circular slide rule of which a movable scale I0! is outlined on the drawings in heavy lines. This movable scale l0l carries an index 102 and double scales I04, I05 corresponding to the characteristics of different film which may be used. The fixed dial 3shows on its periphery two graduation scales A and B placed one following one another. The first scale A is normally used when the illumination is sufllcient so as the light reflected by the view field, the brilliancy of which has to be determined, is sufi'icient to give an indication on the exposure meter; The second scale B is used when the brilliancy of the view field is deficient. In the latter case, the exposure meter may be used to measure the lilumination of the field of view by measuring the radiation directly from the source of light. The utilization of scale A would evidently give too short an exposure time under conditions/of poor illumination, Said B placed ahead of scale A on the periphery of the fixed dial will give a longer, more convenient exposure time. If the exposure time change determined by the passage from mined by the passage from one graduation to another on scale A is /2. For scale B this same exposure time will be changed to a shift of nine graduations and consequently will be 2 or approximately 22.5 times as great as for scale A. This value corresponds to the average ratio between directly received and reflected light. The lack of sensitivity of a photo-sensitive light meter is consequently largely compensated by this arrangement.

, Although in the above description a spherical stepped lens has been illustrated in connection with'Figs. 1, 2 and 3, and a toroidal lens is disclosed in connection with Figs. 4, 5 and 6, it is to be understood that a spherical lens, a stepped spherical lens, or a toroidal lens may be used with either embodiment depending on the value of the viewing angle desired.

The toroidal lens and its mode of mounting permit to obtain a useful angle in the verti- ,having a lens and photo-electric cell aligned along the optical axis, a casing comprising two separate unitary parts which fit together substantially along said optical axis and form an opaque covering open at one end, said lens being adapted to close the open end of said casing, aligned recesses in each ofsaid casing parts adjacent said open end for solely supporting said lens and maintaining it in aligned position, said photo-electric cell being mounted within said casing in a plane spaced a predetermined distance from said lens, aligned recesses in eachof said casing parts in said predetermined plane for maintainingsaid photo-electric cell in a predetermined aligned position, and means for fastening said casing parts together,

' said casing parts serving to retain the parts of said device in position independently of other fastening means.

2. Apparatus as claimed in claim 1, in which said lens is a toroidal lens for producing different desired viewing angles in the horizontal and vertical planes.

3. Apparatus, as claimed. in claim 1, in which said lens comprises'a spherical stepped lens.

4. A photo-electric light measuring device in accordance with claim 1, further comprising a meter responsive to the illumination of said light sensitive cell adapted to be mounted in said casing, a scale on said meter, an opening in said casing, and means comprising further recesses in said casing parts for maintaining said meter in position within said casing in alignment with said opening,

RENE ALPHONSE HIGONNET. LUCIEN DEVAUX. 

